1. Field of the Invention
The present invention relates to a Global System for Mobile communication (GSM) terminal, and more particularly to an apparatus and method for protecting private contents including a primary user's personal information, from unauthorized or secondary users in the GSM terminal.
2. Description of the Related Art
A GSM communication system is a digital mobile phone system widely used in Europe and other countries. GSM Mobile Equipment (hereinafter referred to as an ME) for use in the GSM system is implemented by connecting a GSM Mobile Terminal (hereinafter referred to as an MT) to a Subscriber Identity Module (SIM) card. The SIM card includes information associated with a subscriber ID such as an International Mobile Subscriber Identity (IMSI) and a unit for performing subscriber authentication. The SIM card stores a variety of contents of the primary GSM user, for example, phone book data, short message service (SMS) messages, etc.
The GSM communication system provides a SIM lock function. The SIM lock function reads IMSI contents from among SIM contents to prevent the GSM communication system from being used illegally, and associates the SIM with a specific MT. More specifically, in situations where a primary user's MT is stolen or an unauthorized secondary user attempts to use the primary user's MT, the primary user can lock his or her MT using the SIM lock function to completely prevent the secondary user from using the primary user's MT without authorization. The SIM lock function prevents people other than the primary user from using some functions of the primary user's MT (except an emergency call function) without receiving the primary user's permission. The MT requires a password to release the SIM lock function. Otherwise, if the MT is not supplied with the password, it must receive a SIM card from the user serving as the MT's true owner such that it is enabled to serve as a mobile terminal.
As stated above, the SIM lock function of the conventional GSM ME is adapted to prevent an MT of a primary user from being unfairly used by a secondary user by means of other SIM cards. However, the primary user may lend his or her MT to some other person or secondary user to allow the other person to use the primary user's MT using the other person's SIM card, or the primary user may deposit his or her MT at an after-sale service (AS) center to have his or her MT repaired. In this case, the SIM lock function is far from efficient, such that the primary user's personal or private contents are unavoidably exposed to others even though the primary user wishes not to expose the personal or private contents to the others. In other words, when a friend or a colleague of the primary user, or an engineer working for the AS center insert their SIM cards, instead of the primary user's SIM card, into the primary user's MT, private contents or function setup data stored in the primary user's MT may be unavoidably exposed without any restriction.